A screw type implant fixture includes a body having a screw thread formed on an outer surface thereof and is used as a fixing unit to fix a dental or orthopedic prosthesis or the like into a bone. A bone tissue into which a fixture is to be inserted consists of cancellous and cortical bones. A cancellous bone refers to a relatively soft bone tissue of a bone, and a cortical bone refers to a relatively thin film that is harder than a cancellous bone and generally encloses a cancellous bone. A length of a cancellous bone is usually longer than that of a cortical bone and thus an inserted fixture is implanted into a cancellous bone.
FIG. 1 is a diagram of an implant fixture 100 according to the related art. The implant fixture 100 is formed of a body portion 110 in which a plurality of screw threads 111 are vertically formed, and an entry portion 120 arranged below the body portion 110 and having a cut groove 121 that is formed. The implant fixture 100 according to the related art has a problem in that a torque generated due to inserting of the implant fixture 100 by using repetitive rotation is relatively great at the beginning but is gradually decreased, which reduces an initial fixing force. When the initial fixing force is low, the implant fixture 100 is not certainly implanted in a bone tissue and thus, if an external force is applied to the implant fixture 100, an initial position may be changed or damage may be applied to a peripheral bone tissue.
FIG. 2 is a diagram of an implant fixture 200 according to the related art. The implant fixture 200 according to the related art is formed of a body portion 210 in which a plurality of screw threads are formed, and an entry portion 220 arranged below the body portion 210 and having a cut groove 221 that is formed in the entry portion 220. Here, the body portion 210 is formed of a first part 211 in which a plurality of fine screw threads 211a are formed at an upper part of the body portion 210, and a second part 212 in which a plurality of macro screw threads 212a are formed at a lower part of the body portion 210.
The implant fixture 200 according to the related art is advantageous in that a initial fixing force is relatively great during an insertion procedure due to that the number of the fine screw threads 211a of the first part 211 is increased compared to the number of the macro screw threads 212a of the second part 212, and thus the implant fixture 200 can be firmly implanted into a bone tissue.